In the present day practice of medicine, the alert physician is constantly watchful for tumors or other abnormal growth in the human body which may be malignant. Tumors do not respond to body mechanisms that limit growth. Unlike benign tumors, those which are malignant show an atypical cell structure with undifferentiated rather than functional specialized cells. These malignant cells have a characteristic of invasiveness of surrounding tissue. As a result, early detection is extremely important. Cancers discovered early before metastasis have the best cure rates. Tissue has to be obtained for classification, grading and staging of the disease.
Historically, the open surgical method was utilized for obtaining tissue specimens for examination. This required either local or, sometimes, general anesthesia as well as an incision which was expensive and also associated with more discomfort for the patient and a longer healing period.
The detection of malignancy is presently best determined by examination of an excised portion of the suspect tissue which is removed in the form of wedges or cylindrical pieces by an incursive instrument often referred to as a biopsy needle. Once the tissue specimen is obtained, it is fixed, i.e., killed and coagulated and chemical and histological analyses are carried out. In many instances, the analysis is performed very rapidly during an operation so that the surgeon has a guide to determine the extent of the corrective surgery.
It is desirable that tissue excision be done with as little injury to the surrounding tissue as possible. There are a number of biopsy procedures in use but none are entirely satisfactory. One type relies on suction applied by an attached syringe. This tears the tissue from its base and often fragments are obtained or the needle returns with no specimen. The type of needle which utilizes a cutting mechanism must replace the stylet (slender probe) with a cutting blade or blades and retrieval of the specimen is not always successful. Another type uses suction and a deflector for the blade to cut the tissue but by the very nature of this device the tissue distal to the deflector is lost.
Another type of needle uses a stylet with a partial diametric cut-out a short distance from the tip. This stylet is advanced into the tissue to be tested which is intended to bulge into the recess after which a sheath is brought down over the stylet cutting and trapping the specimen.
It is an object of the present invention to provide a biopsy needle to obtain a specimen which fills the entire volume of the provided recess in the needle sheath and which cuts the tissue clearly and retains it securely for safe retrieval.
It is, therefore, the objective to provide a biopsy needle in which the size of the retrieved specimen corresponds to the designed volume of the biopsy needle. This allows the use of smaller gauge needles to obtain the same quantity of tissue as with the larger types of needles above referenced.
A further object is the clean cutting of the tissue at the base of the incursion so there is no unnecessary incursion and no tearing of the tissue. As a consequence, there is no fragmentation or distortion of the specimen.
The needle is designed to isolate positively the specimen to be cut and is not dependent on an undependable bulging of the tissue. No suction is required in the operation of the needle to be described and no intraluminal stylet is needed.
Another advantage of the present invention is that multiple specimens may be obtained without the need to withdraw the needle.
Two patients which disclose biopsy needles are the U.S. Pat. No. 3,001,522, to Silverman, issued Sept. 26, 1961 and the U.S. Pat. No. 3,007,471, to McClure, Jr., issued Nov. 7, 1961. See also an article by John M, McClure, Jr. in Surgery, vol. 51, April. 1962, page 515. These patents disclose structures which utilize cutting blades for the tissue specimen but each leaves a quantity of tissue contained in the needle.
The most recent instrument used in biopsies is the very thin needle called the skinny needle, but this has the disadvantage that it delivers mostly cells and the interpretation of the sample requires special training and skill which is not always available. Even with highly trained technicians, there are cells which cannot be classified as benign or malignant unless they is a way to study their distribution in the tissue. The tiny specimens do not provide this information. With the "skinny needle" the ratio of the wall thickness to the lumen (the space enclosed by the tubular walls) favors the luman area. The total bulk of the needle is very fine.
With the present invention, the bulk of the biopsy needle can also be very fine. Briefly, my design incorporates a very fine, thin-walled needle in two parts, one of which encloses the major portion of the lumen and the other of which closes the lumen wall and acts as a trocar and cutting blade. A trocar is a stylet with a triangular point.
Other objects and features of the invention will be apparent in the following description and claims in which the invention is described together with details to enable persons skilled in the art to practice the invention, all in connection with the best mode presently contemplated for the invention.